Question

How many molecules of CaCl2 are equivalent to 75.9g CaCl2 (Ca=40.08g/mol, CL=35.45g/mol)

Answer 1

Answer:

$\large \boxed{4.12 \times 10^{23}\text{ formula unis of CaCl}_{2}} }$

Explanation:

You must calculate the moles of CaCl₂, then convert to formula units of CaCl₂.

1. Molar mass of CaCl₂

CaCl₂ = 40.08 + 2×35.45 = 40.08 + 70.90 = 110.98 g/mol

2. Moles of CaCl₂ $\text{Moles of CaCl}_{2} = \text{75.9 g CaCl}_{2} \times \dfrac{\text{1 mol CaCl}_{2}}{\text{110.98 g CaCl}_{2}} = \text{0.6839 mol CaCl}_{2}$

3. Formula units of CaCl₂

$\text{No. of formula units} = \text{0.6839 mol CaCl}_{2} \times \dfrac{6.022 \times 10^{23}\text{ molecules CaCl}_{2}}{\text{1 mol P _{2} O}_{5}}\\\\= \mathbf{4.12 \times 10^{23}}\textbf{ formula units CaCl}_{2}\\\text{There are \large \boxed{\mathbf{4.12 \times 10^{23}}\textbf{ formula units of CaCl}_{2}} }$